Old school links might be a solution. I remember back in the day those blog websites which contained "links" page to the websites that owner likes and recommends. It's true P2P solution and does not require anything to invent. If you own a website and know some rare but valuable gems, just share them. Someone will find them. I think that's how Internet should really work.

As a side effect, it should really help Google and other search engines to rank those websites. External links of good quality still the best SEO.